Full-grain leather-like sheet

Abstract

This full-grain leather-like sheet is provided with a fiber substrate and a resin layer laminated on one surface of the fiber substrate, the resin layer includes at least one skin layer, and the skin layer contains polyurethane, a nonionic compound with an HLB value of 10-16, and a water-soluble polymer, and has a surface free energy with a 25-40 mJ / m2 polar part and a 30-40 mJ / m2 dispersive part, analyzed with OWRK.

Description

Leather-like sheet with silver finish

[0001] The present invention relates to a grain-finish leather-like sheet that has high wettability, high water resistance, and high secondary adhesiveness.

[0002] Grain-finish leather-like sheets, such as artificial leather and synthetic leather, which have a grain-finish resin layer, are known as materials for shoes, bags, clothing, etc. A typical grain-finish leather-like sheet comprises a fiber substrate and a polyurethane-containing resin layer laminated on the fiber substrate.

[0003] In recent years, in order to reduce the environmental impact in the production of grain-finish leather-like sheets, there has been a demand for a production method that uses an aqueous polyurethane liquid, such as an emulsion obtained by dispersing an aqueous polyurethane dispersible in an aqueous medium, and that reduces the amount of organic solvent used. For example, Patent Document 1 below discloses a grain-finish artificial leather having a grain surface layer formed using an aqueous polyurethane resin dispersion on at least one side of a substrate layer made of a three-dimensionally entangled nonwoven fabric and a polymeric elastomer applied using an aqueous resin dispersion.

[0004] Furthermore, Patent Document 2 listed below discloses a method for producing a porous structure used in producing leather-like sheets, which comprises applying to a substrate a mixed liquid containing (A) an aqueous thermoplastic binder liquid, (B) a urethane prepolymer terminated with an isocyanate block, and at least one selected from the group consisting of (C) an inorganic compound, (D) a water-soluble organic polymer, and (E) a high-cloud-point surfactant, followed by forming a porous body by wet heating with steam, or by heating in combination with high-frequency heating or high-frequency dielectric heating, and then drying the resulting porous body.

[0005] When grain-finish leather-like sheets are processed into secondary products such as shoes, bags, and clothing, surface treatment properties and secondary adhesion to the grain-finish resin layer are required. The surface treatment properties of grain-finish leather-like sheets refer to a process in which a treatment liquid containing a pigment, a matting agent, an antibacterial agent, etc. is applied to the surface of the resin layer by gravure coating or the like to adjust the surface properties. The secondary adhesion properties of grain-finish leather-like sheets refer to the adhesion properties when other materials are bonded to the surface of the grain-finish resin layer with an adhesive.

[0006] When the polyurethane for forming the grain-finish resin layer is an aqueous polyurethane formed using an aqueous polyurethane liquid, it often contains a relatively highly hydrophobic aqueous polyurethane in order to maintain the storage stability of the aqueous polyurethane liquid. When the grain-finish resin layer is formed using an aqueous polyurethane liquid containing such a relatively highly hydrophobic aqueous polyurethane, the hydrophobicity of the surface of the resin layer also increases, resulting in a problem of reduced wettability with highly polar aqueous treatment solutions.

[0007] To solve these problems, for example, Patent Document 3 below discloses a leather-like sheet in which a surface layer is formed by applying a urethane resin composition for forming a surface layer containing an aqueous polyurethane onto a release sheet and drying the composition, and then laminating the surface layer and a fiber substrate with an adhesive. Patent Document 3 also discloses that the ratio of hydrophilic and hydrophobic components is adjusted to improve the polarity of the aqueous polyurethane, thereby improving secondary adhesion while maintaining water resistance.

[0008] Japanese Patent Application Laid-Open No. 2003-155672 Japanese Patent Application Laid-Open No. 2002-249987 International Publication No. 2012 / 017724 Pamphlet

[0009] To produce a highly water-resistant grain-finish leather-like sheet, a resin layer containing a highly water-resistant polyurethane is often employed. In the leather-like sheet disclosed in Patent Document 3, if the surface water resistance of the resin layer is increased, it becomes difficult to sufficiently improve polarity. Therefore, in the leather-like sheet disclosed in Patent Document 3, if the water resistance is increased further, it is believed that the sufficiently high wettability with aqueous liquids required for surface treatment with highly polar treatment solutions cannot be obtained. Furthermore, if the ratio of hydrophilic components in the polyurethane is increased to increase the surface wettability of the resin layer, it is believed that the water resistance will decrease. Thus, there is a trade-off between the surface wettability and water resistance of the resin layer.

[0010] Furthermore, as mentioned above, grain-finish leather-like sheets are sometimes required to have high secondary adhesion. Conventional resin layers containing aqueous polyurethanes have low secondary adhesion even though they have high wettability.

[0011] Thus, no grain-finish leather-like sheet has been obtained that has high wettability with respect to aqueous liquids, high water resistance, and high secondary adhesiveness.

[0012] An object of the present invention is to provide a grain-finish leather-like sheet that has high wettability with respect to aqueous liquids, high water resistance, and high secondary adhesiveness.

[0013] One aspect of the present invention is a grain-finish leather-like sheet comprising a fiber substrate and a resin layer laminated on one surface of the fiber substrate, the resin layer including at least a surface layer. The surface layer contains polyurethane, a nonionic compound having an HLB value of 10 to 16, and a water-soluble polymer, and has a polar component of 25 to 40 mJ / m as analyzed by the Owens-Wendt-Rabel-Kaelble method (hereinafter also referred to as the OWRK method). 2 and the dispersion component is 30 to 40 mJ / m 2 The surface free energy of the grain-finish leather-like sheet is 1 / 2.0000. The grain-finish leather-like sheet has a resin layer surface that exhibits high wettability, high water resistance, and high secondary adhesiveness. The polyurethane is usually an aqueous polyurethane that can be dispersed in an aqueous medium.

[0014] In addition, polyurethane has a polar component of 5 to 20 mJ / m as analyzed by the OWRK method. 2 and the dispersion component is 30 to 40 mJ / m 2 It is preferable that the surface free energy is such that a grain-finish leather-like sheet having high wettability, high water resistance, and high secondary adhesiveness can be easily obtained.

[0015] Furthermore, it is preferable that the nonionic compound contains at least one selected from the group consisting of silicone-based compounds and acetylene glycol-based compounds, since even a small amount of addition can significantly improve the surface free energy.

[0016] The surface layer preferably contains 0.8 to 5.0% by mass of a nonionic compound, since this makes it easier to maintain sufficient wettability without reducing water resistance or secondary adhesiveness.

[0017] Furthermore, it is preferable that the water-soluble polymer has a number average molecular weight of 10,000 to 150,000, and further that the water-soluble polymer is contained in an amount of 1.0 to 10 mass %, from the viewpoint of easily maintaining high secondary adhesiveness without reducing water resistance.

[0018] Furthermore, it is preferable that the skin layer is a continuous film having no pores and a thickness of 10 to 100 μm, since this provides an elegant appearance without any recesses such as sunken portions on the surface of the skin layer.

[0019] Furthermore, it is preferable that the resin layer includes at least an adhesive layer having a thickness of 30 to 120 μm, which contains polyurethane and adheres the fiber substrate, in order to firmly adhere the resin layer to the fiber substrate.

[0020] According to the present invention, a grain-finish leather-like sheet can be obtained which has high wettability with respect to aqueous liquids, high water resistance, and high secondary adhesiveness.

[0021] 1 is a schematic cross-sectional view illustrating the layer structure of a grain-finish leather-like sheet 10, which is an example of an embodiment.

[0022] Hereinafter, the present invention will be described in detail with reference to one embodiment of a grain-finish leather-like sheet.

[0023] Referring to Figure 1, a grain-finish leather-like sheet 10, which is an example of an embodiment, comprises a fiber substrate 1 and a resin layer 2 laminated on one surface of the fiber substrate 1. The resin layer 2 includes a surface layer 2a, an intermediate layer 2b, and an adhesive layer 2c.

[0024] The adhesive layer 2c is a layer mainly made of polyurethane and disposed to bond the resin layer 2 to the fiber base material 1. The intermediate layer 2b interposed between the surface layer 2a and the adhesive layer 2c is a layer mainly made of polyurethane and selected depending on the purpose, such as adjusting the texture of the surface.

[0025] The surface layer 2a is preferably disposed on the outermost surface of the resin layer and is a layer mainly made of polyurethane for imparting high wettability, high water resistance, and high secondary adhesiveness to the surface of the resin layer. Specifically, the surface layer 2a contains at least polyurethane, a nonionic compound having an HLB value of 10 to 16, and a water-soluble polymer, and has a polar component of 25 to 40 mJ / m as analyzed by the OWRK method.2 and the dispersion component is 30 to 40 mJ / m 2 The layer is mainly made of polyurethane having a surface free energy of

[0026] The grain-finish leather-like sheet of this embodiment, as exemplified by grain-finish leather-like sheet 10, comprises a resin layer laminated on one side of a fiber substrate and including at least a surface layer containing polyurethane, a nonionic compound with an HLB value of 10 to 16, and a water-soluble polymer. Such a resin layer gives the grain-finish leather-like sheet a grain-finish appearance. The resin layer may also include other layers, such as an adhesive layer for bonding the surface layer to the fiber substrate and an intermediate layer for adjusting the surface texture, as described above.

[0027] The fiber substrate is a woven fabric, a knitted fabric, a nonwoven fabric, or a combination of these entangled fibers. Among these, a nonwoven fabric is particularly preferred because it maintains a supple texture. The fiber substrate may also contain a polymeric elastomer impregnated into the voids of the entangled fiber.

[0028] The type of resin forming the fibers is not particularly limited. Specific examples include aromatic polyesters such as polyethylene terephthalate (PET), isophthalic acid-modified polyethylene terephthalate, sulfoisophthalic acid-modified polyethylene terephthalate, polybutylene terephthalate, and polyhexamethylene terephthalate; fatty acid polyesters such as polylactic acid, polyethylene succinate, polybutylene succinate, polybutylene succinate adipate, and polyhydroxybutyrate-polyhydroxyvalerate copolymer; nylons such as nylon 6, nylon 66, nylon 10, nylon 11, nylon 12, and nylon 6-12; polyolefins such as polypropylene, polyethylene, polybutene, polymethylpentene, and chlorinated polyolefins; modified polyvinyl alcohols such as modified polyvinyl alcohols containing 25 to 70 mol% ethylene units; and elastomers such as polyurethane elastomers, polyamide elastomers, and polyester elastomers. Among these, PET, isophthalic acid-modified polyethylene terephthalate, polylactic acid, nylon 6, nylon 12, nylon 6-12, nylon copolymers, and polypropylene are particularly preferred because of their excellent spinnability and the mechanical properties of the resulting artificial leather. These resins may be used alone or in combination of two or more.

[0029] The fineness of the fibers forming the fiber substrate is not particularly limited, but for example, ultrafine fibers with an average fineness of 0.001 to 0.5 dtex are particularly preferred in terms of obtaining a supple feel.

[0030] The fiber substrate may also contain a polymeric elastomer impregnated into the voids of the entangled fiber structure. Specific examples of the polymeric elastomer impregnated into the voids of the entangled fiber structure include polyurethane, acrylonitrile elastomer, olefin elastomer, polyester elastomer, polyamide elastomer, and acrylic elastomer. Among these, crosslinked aqueous polyurethane obtained by coagulating a polyurethane emulsion is particularly preferred because it can reduce the amount of organic solvent used.

[0031] The content of the elastomer in the fiber substrate is not particularly limited, but is preferably 5 to 60 mass %, more preferably 8 to 40 mass %. The thickness of the fiber substrate is not particularly limited, but is preferably 0.2 to 3.0 mm.

[0032] The grain-finish leather-like sheet of this embodiment, as exemplified by grain-finish leather-like sheet 10, comprises a resin layer laminated on one side of a fiber substrate and including at least a surface layer containing polyurethane, a nonionic compound with an HLB value of 10 to 16, and a water-soluble polymer. Such a resin layer gives the grain-finish leather-like sheet a grain-finish appearance. The resin layer may also include other layers, such as an adhesive layer for bonding the surface layer to the fiber substrate and an intermediate layer for adjusting the surface texture, as described above.

[0033] The polyurethane in this embodiment is preferably an aqueous polyurethane derived from an aqueous polyurethane dispersion, which is an emulsion or dispersion in which polyurethane or its prepolymer is dispersed in water or a water-based aqueous medium. Aqueous polyurethanes are distinct from solvent-based polyurethanes, which are derived from solutions of polyurethane dissolved in organic solvents. Aqueous polyurethanes are obtained, for example, by reacting urethane raw materials containing a polymer polyol, an organic polyisocyanate, a chain extender, and, optionally, a polyfunctional compound.

[0034] Specific examples of polymer polyols include polyether polyols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and poly(methyltetramethylene glycol), and copolymers thereof; polyester polyols such as polybutylene adipate diol, polybutylene sebacate diol, polyhexamethylene adipate diol, poly(3-methyl-1,5-pentylene adipate) diol, poly(3-methyl-1,5-pentylene sebacate) diol, and polycaprolactone diol, and copolymers thereof; polycarbonate polyols such as polyhexamethylene carbonate diol, poly(3-methyl-1,5-pentylene carbonate) diol, polypentamethylene carbonate diol, and polytetramethylene carbonate diol, and copolymers thereof; polyester carbonate polyols, etc. If necessary, polyfunctional alcohols such as trifunctional alcohols and tetrafunctional alcohols, or short-chain alcohols such as ethylene glycol, may be used in combination. These may be used alone or in combination of two or more.

[0035] Specific examples of organic polyisocyanates include non-yellowing diisocyanates such as aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate; and aromatic diisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate. If necessary, polyfunctional isocyanates such as trifunctional isocyanates may also be used in combination. These may be used alone or in combination of two or more.

[0036] Specific examples of chain extenders include diamines such as hydrazine, ethylenediamine, propylenediamine, hexamethylenediamine, nonamethylenediamine, xylylenediamine, isophoronediamine, piperazine and its derivatives, adipic acid dihydrazide, and isophthalic acid dihydrazide; triamines such as diethylenetriamine; tetramines such as triethylenetetramine; diols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-bis(β-hydroxyethoxy)benzene, and 1,4-cyclohexanediol; triols such as trimethylolpropane; pentaols such as pentaerythritol; and aminoalcohols such as aminoethyl alcohol and aminopropyl alcohol. These may be used alone or in combination of two or more.

[0037] Examples of crosslinking agents include bifunctional polyisocyanate compounds, which form crosslinked structures with hydroxyl groups or amino groups; polyfunctional isocyanate compounds such as biuret, adduct, and isocyanurate; and compounds having carbodiimide groups, oxazoline groups, epoxy groups, cyclocarbonate groups, and aziridine groups, as well as hydrazine derivatives and hydrazide derivatives, which form crosslinked structures with carboxyl groups. These may be used alone or in combination of two or more. When a crosslinking agent is used, the blending ratio of the crosslinking agent is preferably 2 to 20% by mass relative to the aqueous polyurethane.

[0038] Preferably, the surface layer disposed as the outermost layer of the resin layer contains at least polyurethane, a nonionic compound having an HLB value of 10 to 16, and a water-soluble polymer, and has a polar component of 25 to 40 mJ / m as analyzed by the OWRK method. 2 and the dispersion component is 30 to 40 mJ / m 2 The surface layer preferably contains 90% by mass or more, and more preferably 95% by mass or more, of the resin component of the surface layer as aqueous polyurethane.

[0039] Here, surface free energy refers to the surface tension, which is the sum of the components of intermolecular forces possessed by a solid. The polar and dispersive components of surface free energy, analyzed using the Owens-Wendt-Rabel-Kaelble (OWRK) method, are the components of intermolecular forces of surface free energy, respectively. The polar component reflects the orientational force of the solid, and the dispersive component reflects the dispersion force of the solid.

[0040] The skin layer of this embodiment has a polar component of 25 to 40 mJ / m as analyzed by the OWRK method. 2 and the dispersion component is 30 to 40 mJ / m 2 When the surface layer has such a polar component and dispersive component of the surface free energy, a grain-finish leather-like sheet having an excellent balance between water resistance and wettability can be obtained.

[0041] The polar component of the surface free energy of the epidermal layer is 25 mJ / m 2 If the polar component of the surface free energy of the surface layer is less than 40 mJ / m, the wettability is likely to decrease. 2 If the dispersion component of the surface free energy of the skin layer exceeds 30 mJ / m 2 If the dispersion component of the surface free energy of the surface layer is less than 40 mJ / m, the secondary adhesiveness tends to be reduced. 2 If it exceeds this value, the wettability is likely to decrease.

[0042] A surface layer having such a surface free energy can be obtained by adjusting the type of polyurethane contained in the surface layer and the types and addition ratios of a nonionic compound and a water-soluble polymer having an HLB value of 10 to 16 that are added to adjust the surface free energy of the surface layer.

[0043] The polyurethane contained in the surface layer has a polar component of 3 to 25 mJ / m 2 , and even 10 to 20 mJ / m 2 and the dispersion component is 30 to 40 mJ / m 2It is preferable to use an aqueous polyurethane having a surface free energy of 10 to 16. Here, the surface free energy of polyurethane means the surface free energy of polyurethane that does not contain a nonionic compound or a water-soluble polymer and has an HLB value of 10 to 16.

[0044] The polar and dispersive components of the surface free energy of polyurethanes can be varied by adjusting the ratio of hydrophilic to hydrophobic components of the soft segments derived from the polymeric polyol units of the polyurethane.

[0045] Specifically, increasing the ratio of the hydrophilic component in the polymer polyol increases the polar component, while increasing the ratio of the hydrophobic component increases the dispersive component. When the polar component of the surface free energy of the polyurethane is large, the polar component of the surface free energy of the skin layer also increases, and when the dispersive component is large, the dispersive component of the surface free energy of the skin layer also increases.

[0046] The hydrophilic component of the soft segment is derived from a polymer polyol unit whose repeating structure, excluding ester bonds, has a carbon number of 1 to 3. Specific examples of polymer polyols that serve as such hydrophilic components include polymer polyols having 2 carbon atoms, such as polyethylene glycol, and polymer polyols having 3 carbon atoms, such as polypropylene glycol.

[0047] The hydrophobic component of the soft segment is derived from a polymer polyol unit whose repeating structure, excluding ester bonds, has 4 to 6 carbon atoms. Specific examples of polymer polyols that serve as such hydrophobic components include polymer polyols having 4 carbon atoms, such as polytetramethylene glycol, polymer polyols having 5 carbon atoms, such as polypentamethylene glycol, and polymer polyols having 6 carbon atoms, such as polyhexamethylene carbonate diol.

[0048] The polar component of the surface free energy of the polyurethane adjusted as described above is 3 to 25 mJ / m 2 , and even 10 to 20 mJ / m 2This is preferable because it maintains water resistance while also providing excellent secondary adhesion. If the polar component of the surface free energy of the polyurethane is too small, the polar component of the surface layer also becomes small, which tends to reduce adhesion to adhesives, thermoplastic urethane resins, etc., and therefore reduce secondary adhesion. On the other hand, if the polar component of the surface free energy of the polyurethane is too large, the polar component of the surface layer also becomes large, which increases secondary adhesion but tends to reduce water resistance.

[0049] The dispersion component of the surface free energy of polyurethane is 30 to 40 mJ / m 2 This is preferred from the viewpoint of achieving an excellent balance between water resistance and secondary adhesiveness. If the dispersion component of the surface free energy of the polyurethane is too small, the secondary adhesiveness tends to decrease.

[0050] Specific examples of such polyurethanes include aqueous polyurethanes contained in Hydran ULK-190 and Hydran ULK-003 manufactured by DIC Corporation, which are polyurethane emulsions.

[0051] The surface layer contains a nonionic compound with an HLB value of 10 to 16. The HLB value (Hydrophilic-Lipophilic Balance) is a value that indicates the degree of affinity of a surfactant for water and oil. The HLB value ranges from 0 to 20, with the closer to 0 the higher the lipophilicity and the closer to 20 the higher the hydrophilicity. By incorporating a nonionic compound with an HLB value of 10 to 16 into the surface layer, the surface free energy of the surface layer can be increased, improving the wettability required for surface treatment of the surface layer. The HLB value can be calculated, for example, by the Griffin method, using the formula: HLB value = 20 x (sum of molecular weights of hydrophilic moieties / total molecular weight).

[0052] By incorporating a nonionic compound with an HLB value of 10 to 16 into the surface layer, the polar component of the surface of the surface layer can be increased, thereby improving wettability. On the other hand, incorporating a nonionic compound with an HLB value of 10 to 16 into the surface layer does not easily improve secondary adhesion.

[0053] If the HLB value of the nonionic compound is less than 10, the hydrophilicity of the nonionic compound is too low, making it difficult to sufficiently increase the polar component of the surface free energy of the surface layer. On the other hand, if the HLB value of the nonionic compound is more than 16, the hydrophilicity of the nonionic compound is too high, tending to reduce the water resistance of the surface layer.

[0054] Specific examples of nonionic compounds having an HLB value of 10 to 16 include silicone compounds such as polysiloxanes, e.g., polyether-modified polydimethylsiloxanes; acetylene glycol compounds; polyoxyethylene alkyl ether compounds; polyoxyethylene alkyl allyl ether compounds; polyoxyethylene-polyoxypropylene block copolymer compounds; and fluorine compounds, e.g., organic fluoro compounds, all of which have an HLB value of 10 to 16. These compounds may be used alone or in combination of two or more. Among these, silicone compounds or acetylene glycol compounds, particularly polyether-modified polydimethylsiloxane compounds, are preferred because they can significantly improve surface free energy with the addition of a small amount.

[0055] The content of the nonionic compound having an HLB value of 10 to 16 in the surface layer is preferably 0.8 to 5.0 mass%, and more preferably 1.2 to 4.0 mass%. If the content of the nonionic compound having an HLB value of 10 to 16 is too low, the surface free energy of the surface layer will not be sufficiently improved, and wettability will tend to be insufficiently improved. On the other hand, if the content of the nonionic compound having an HLB value of 10 to 16 is too high, there is a concern that the nonionic compound will bleed onto the surface of the surface layer, reducing water resistance and secondary adhesion.

[0056] The skin layer also contains a water-soluble polymer, which has a large polar component in its surface free energy and therefore easily penetrates into the molecular network of the aqueous polyurethane contained in the skin layer, thereby increasing the polar component of the skin layer and improving secondary adhesion.

[0057] As described above, the polar component of the polyurethane can be increased by increasing the ratio of the hydrophilic component in the soft segment of the polyurethane. However, if the ratio of the hydrophilic component in the soft segment of the polyurethane is increased and the polar component is increased too much, the polyurethane becomes more likely to swell in water, resulting in a decrease in water resistance. In the surface layer of this embodiment, by incorporating a water-soluble polymer, it is possible to selectively improve secondary adhesion without increasing the polar component of the polyurethane too much, thereby reducing water resistance.

[0058] The water-soluble polymer is a polymer that can be mixed with water to prepare a solution of 10 g or more dissolved in 1 L of water. Specific examples include polyurethane-modified polyoxyalkylene, polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, etc. These may be used alone or in combination of two or more. Among these, polyurethane-modified polyoxyalkylene is particularly preferred because it has a strong interaction with aqueous polyurethane and therefore easily penetrates into the molecular network of polyurethane contained in the surface layer, thereby easily increasing the polarity of the surface layer.

[0059] The number-average molecular weight of the water-soluble polymer is 10,000 or more, preferably 10,000 to 150,000, and more preferably 30,000 to 120,000. If the number-average molecular weight is too low, the effect of improving secondary adhesiveness tends to be small. On the other hand, if the number-average molecular weight is too high, water resistance tends to decrease.

[0060] The content of the water-soluble polymer in the surface layer is preferably 1.0 to 10% by mass, and more preferably 2.0 to 8.0% by mass. If the content of the water-soluble polymer is too low, the polar component of the surface free energy of the surface layer tends not to be sufficiently large. On the other hand, if the content of the water-soluble polymer is too high, there is a concern that the water resistance of the surface layer may decrease.

[0061] The surface layer may contain additives such as antifoaming agents, leveling agents, thickeners, pigments, dyes, matting agents, organic solvents, and resin beads, as needed, within the range that does not impair the effects of the present invention.

[0062] The thickness of the skin layer is not particularly limited, but is preferably 10 to 100 μm, more preferably 10 to 50 μm. The thickness of the skin layer can be calculated, for example, from a cross-sectional photograph taken with a scanning electron microscope (SEM).

[0063] Furthermore, it is preferable that the skin layer be a continuous film without pores, since this provides an elegant appearance without any sunken depressions on the surface of the skin layer. If the skin layer has pores, sunken depressions may appear on the surface of the skin layer when processed into a secondary product, resulting in poor appearance.

[0064] The resin layer contained in the grain-finish leather-like sheet of this embodiment includes at least the surface layer as described above, and may further include layers containing other resins, such as an adhesive layer arranged to bond the surface layer to the fiber substrate, or an intermediate layer to adjust the surface texture, as necessary.

[0065] Next, an example of a method for producing the grain-finish leather-like sheet of this embodiment will be described. The method for producing the grain-finish leather-like sheet of this embodiment is the same as the method for producing a conventional grain-finish leather-like sheet, except that the resin layer that gives the grain-finish appearance contains the surface layer as described above.

[0066] For example, a fiber substrate as described above is prepared, and a resin layer for imparting a grain-like appearance to one surface of the fiber substrate is formed. Specifically, for example, a dry surface forming method is used in which a film that becomes the resin layer formed on a release paper is adhered to the surface of the fiber substrate, and the release paper is peeled off to laminate and adhere the resin layer to the fiber substrate.

[0067] Specifically, first, a coating liquid for forming a surface layer is applied onto a release paper, and then dried to form a film that will become the surface layer.

[0068] The coating liquid for the surface layer is prepared by mixing an aqueous polyurethane liquid such as an emulsion or dispersion containing aqueous polyurethane, a nonionic compound having an HLB value of 10 to 16, a water-soluble polymer, and optionally a crosslinking agent or additives. The water-soluble polymer and the nonionic compound having an HLB value of 10 to 16 are preferably mixed in the form of a liquid such as an aqueous solution or oil, as this facilitates mixing.

[0069] The solids concentration of the aqueous polyurethane in the aqueous polyurethane liquid is not particularly limited, but is preferably about 20 to 60 mass %. The solids concentration of the aqueous solution of the water-soluble polymer is also not particularly limited, but is preferably about 20 to 60 mass %.

[0070] The coating liquid for the surface layer is then applied onto the release paper and dried. The drying conditions are not particularly limited, but drying at 70 to 130°C for 1 to 10 minutes is preferred. In this way, a coating that will become the surface layer is formed on the release paper.

[0071] Then, a coating to become an intermediate layer or an adhesive layer is formed on the surface of the coating to become the surface layer formed on the release paper. The resin for forming the intermediate layer or adhesive layer is not particularly limited, but polyurethane is preferable in terms of excellent adhesion to other layers. Furthermore, aqueous polyurethane is particularly preferable in terms of being able to reduce the amount of organic solvent used.

[0072] The polyurethane used in the adhesive layer may be a solvent-based polyurethane dissolved in an organic solvent or the like, or may be an aqueous polyurethane, but an aqueous polyurethane is preferred because it can reduce the amount of organic solvent used. In addition, it is preferable to blend a crosslinking agent in the adhesive layer to improve adhesion to the substrate.

[0073] The crosslinking agent for polyurethane used in the adhesive layer may be any known crosslinking agent for polyurethane, without any particular limitation. Specific examples include epoxy compounds, aziridine compounds, carbodiimide compounds, organic polyisocyanate compounds, oxazoline compounds, melamine formamide compounds, and ureamethylol compounds. These may be used alone or in combination of two or more.

[0074] The intermediate layer is a layer that is disposed as needed to adjust the thickness of the grain-finish resin layer of the grain-finish leather-like sheet. The polyurethane used in the intermediate layer may be a solvent-based polyurethane dissolved in an organic solvent or may be an aqueous polyurethane, but an aqueous polyurethane is preferred because it can reduce the amount of organic solvent used.

[0075] The adhesive layer is formed by applying an adhesive layer coating liquid to the surface of the film that will become the surface layer formed on the release paper and drying it. When an intermediate layer is formed, the intermediate layer is formed by applying an intermediate layer coating liquid to the surface of the film that will become the surface layer formed on the release paper and drying it. When an intermediate layer is formed, the adhesive layer is formed by applying an adhesive layer coating liquid to the surface of the film that is formed by laminating the surface layer and the intermediate layer formed on the release paper and drying it. Each layer may be a single layer, or may consist of multiple layers formed from coating liquids of different compositions. The film that will become the intermediate layer and the film that will become the adhesive layer are also formed in the same way as the film that will become the surface layer.

[0076] The thickness of the intermediate layer is not particularly limited, but is preferably about 10 to 50 μm, and more preferably about 20 to 40 μm. The thickness of the adhesive layer is also not particularly limited, but is preferably about 30 to 130 μm, and more preferably about 50 to 100 μm.

[0077] The resulting laminate (adhesive layer / surface layer / release paper, or adhesive layer / intermediate layer / surface layer / release paper) is then laminated onto the surface of the fiber substrate via the adhesive layer, and pressed with a clearance roll or the like to adhere a resin layer to the surface of the fiber substrate. If necessary, the laminate may be aged at 40 to 90°C for 1 to 3 days to promote crosslinking of the polyurethane contained in the adhesive layer. The release paper is then peeled off from the resulting laminate to obtain a grain-finish leather-like sheet.

[0078] The grain-finish leather-like sheet obtained in this way is excellent in processability for secondary products such as shoes, bags, and clothing. Specifically, when a treatment liquid containing a pigment, a matting agent, an antibacterial agent, etc. is applied to the surface of the resin layer by gravure coating or the like, it exhibits excellent wettability with highly polar aqueous treatment liquids. Furthermore, when other materials are bonded to the surface of the resin layer with an adhesive, it exhibits particularly excellent adhesion to adhesives containing aqueous polyurethanes and hot-melt polyurethane adhesives.

[0079] The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited to the examples. In the following, parts and percentages are by mass unless otherwise specified.

[0080] First, the evaluation methods used in the examples will be summarized below.

[0081] [Calculation of Polar and Dispersive Components of the Surface Free Energy of Polyurethane and Surface Skin Layer] Using pure water and diiodomethane (methylene iodide) as test liquids, the polar and dispersive components of the surface free energy of polyurethane and surface skin layer were analyzed by the OWRK method. Specifically, for the surface free energy of polyurethane, a polyurethane emulsion was poured into a mold of a predetermined size lined with release paper having a smooth surface, and the emulsion was dried to form a polyurethane film approximately 50 mm thick. Then, 1 μL droplets of pure water and diiodomethane were dropped onto the surface of the polyurethane film using a syringe, and the contact angles of each droplet were measured using a contact angle meter (CA-DT, manufactured by Kyowa Interface Science Co., Ltd.). The measurement environment was 25°C and 50% RH. The polar component γ of the surface free energy of the polyurethane film surface was calculated by solving simultaneous equations using the following equation (1) based on the OWRK analysis: ｐ and the variance component γ ｄ 1 + cos θ = 2 [(γ ｄ ・γ Ｌ ｄ ) / γ Ｌ ２ ] １／２ +2[(γ ｐ ・γ Ｌｐ ) / γ Ｌ ２ ] １／２　 ...Equation (1) The symbols in equation (1) represent the following: γ ｄ : Dispersion component of surface free energy of polyurethane film surface (mJ / m 2 ) ・γ ｐ : Polar component of the surface free energy of the polyurethane film surface (mJ / m 2 ) θ: Contact angle of each test liquid (°) γ Ｌ ｄ : Dispersion component of surface free energy of each test liquid (mJ / m 2 ) (Water: 21.8mJ / m 2 , diiodomethane: 49.5 mJ / m 2 ) ・γ Ｌ ｐ : Polar component of surface free energy of each test liquid (mJ / m 2 ) (Water: 51.0mJ / m 2 , diiodomethane: 1.3 mJ / m 2 ) ・γ Ｌ Similarly, a coating film was formed using a coating liquid for forming the surface layer of the grain-finish leather-like sheet, and the contact angles of the surface of the skin layer with pure water and diiodomethane were measured. The polar component γ of the surface free energy of the surface layer of the grain-finish leather-like sheet was calculated using equation (1) based on OWRK analysis. ｐ and the variance component γ ｄ and was calculated.

[0082] [Number Average Molecular Weight of Water-Soluble Polymer] The number average molecular weight was determined by gel permeation chromatography (GPC) under the following conditions, and expressed as a value converted into standard polystyrene. (GPC Measurement Conditions) Apparatus: "CBM-20A" manufactured by Shimadzu Corporation Mobile phase: N,N-dimethylformamide (flow rate: 1 mL / min) Column: KD-806M manufactured by Shodex Detector: differential refractometer Measurement temperature: 40°C Standard material: polystyrene manufactured by Tosoh Corporation Injection volume: 50 μL Sample concentration: 2 mg / 2 cc

[0083] [Water Resistance of Surface Layer] A 3 cm x 3 cm piece of film was cut out from the film forming the surface layer of the grain-finish leather-like sheet. The film piece was then immersed in water at 25°C for 24 hours and then removed. Immediately after removal, excess water was wiped off the film piece, and the weight swelling ratio (%) was measured and calculated according to the following formula: Weight swelling ratio (%) = {(Weight after swelling - Weight before immersion) / Weight before immersion} x 100 Based on the obtained weight swelling ratio value, the water resistance was evaluated according to the following evaluation criteria: Excellent: Weight swelling ratio less than 5% Good: Weight swelling ratio 5% or more but less than 15% Poor: Weight swelling ratio 15% or more

[0084] [Surface wettability of surface of surface layer] The surface wettability of the surface layer of the grain-finish leather-like sheet was measured in accordance with JIS K 6768. Specifically, a mixture for wetting tension test (mixture for wetting tension test manufactured by Kanto Chemical Co., Ltd.: 65 mJ / m 2 ) was applied to a wet film thickness of 12 μm using a non-wire bar coater. If the liquid film did not break for 5 seconds or more, it was evaluated as "high", if it broke within 2 seconds or more but less than 5 seconds, it was evaluated as "medium", and if it broke in less than 2 seconds, it was evaluated as "low".

[0085] [Secondary Adhesion of the Surface of the Skin Layer] A grain-finish leather-like sheet, a hot melt tape, and a plain weave fabric were cut into strips measuring 150 mm lengthwise and 30 mm widthwise. The hot melt tape used was a thermoplastic urethane-based hot melt tape (NASA-T manufactured by Sambu Fine Chemical) with a thickness of 200 μm. The basis weight of the plain weave fabric was 1.3 g / m². 2 The stack, in which the hot melt tape and the plain woven fabric were laminated in this order on the surface of the surface layer of the grain-finish leather-like sheet, was subjected to a pressure of 6 kgf / cm at a temperature of 130°C. ２ A test piece was prepared by pressing the test piece at a pressure of 1000 kJ / cm for 30 seconds. Note that only one end portion was left unbonded in a region extending 30 mm in the longitudinal direction from the end portion, and the remaining region extending 120 mm in the longitudinal direction was bonded.

[0086] The peel strength of the hot melt tape adhered to the surface of the skin layer of the grain-finish leather-like sheet was measured using a tensile tester. Specifically, one end of the unbonded side of the grain-finish leather-like sheet and one end of the unbonded side of the plain weave fabric of the obtained test piece were clamped between the upper and lower chucks of the tensile tester, and the peel strength between the hot melt tape and the surface of the skin layer was measured at a test speed of 50 mm / min. The peel strength was evaluated as "excellent" when it was 3.0 kg / cm or more and peeling occurred with material failure of the skin layer, "good" when it was 3.0 kg / cm or more but no material failure of the skin layer, and "poor" when it was less than 3.0 kg / cm.

[0087] The raw materials used in this example will be summarized below.

[0088] (Polyurethane emulsions for surface layer) Emulsion of polyurethane A: Emulsion of polyether-based polyurethane with 35% solids (Hydran ULK-190, manufactured by DIC Corporation) Emulsion of polyurethane B: Emulsion of polyether-based polyurethane with 30% solids (Hydran ULK-003, manufactured by DIC Corporation) Emulsion of polyurethane C: Emulsion of polyester / polyether-based polyurethane with 45% solids (Hydran CRS-086, manufactured by DIC Corporation) Emulsion of polyurethane D: Emulsion of anionic self-emulsifying polycarbonate-based polyurethane with 40% solids (100% modulus 3.0 MPa) Emulsion of polyurethane E: Emulsion of polycarbonate-based polyurethane with 30% solids (Hydran WLS-290SG, manufactured by DIC Corporation)

[0089] (Polyurethane emulsion for adhesive layer) Polyether polyurethane emulsion with a solid content of 55% (Hydran WLA-451TA, manufactured by DIC Corporation)

[0090] (Nonionic Compounds) Nonionic compound E: a silicone compound having an HLB value of 12 (polyether-modified polydimethylsiloxane, silicone oil KF-351A manufactured by Shin-Etsu Chemical Co., Ltd.) Nonionic compound F: a silicone compound having an HLB value of 10 (polyether-modified polydimethylsiloxane, silicone oil KF-353 manufactured by Shin-Etsu Chemical Co., Ltd.) Nonionic compound G: a silicone compound having an HLB value of 16 (polyether-modified polydimethylsiloxane, silicone oil KF-354L manufactured by Shin-Etsu Chemical Co., Ltd.) Nonionic compound H: a silicone compound having an HLB value of 7 (polyether-modified polydimethylsiloxane, silicone oil KF-352A manufactured by Shin-Etsu Chemical Co., Ltd.) Nonionic compound I: an acetylene glycol-based nonionic surfactant having an HLB value of 13 (Surfynol 465, manufactured by Nissin Chemical Industry Co., Ltd.); Nonionic compound X: a polyoxyethylene alkyl ether-based nonionic compound having an HLB value of 18 (NIKKOL BC-23, manufactured by Nikko Chemicals Co., Ltd.).

[0091] (Aqueous solutions of water-soluble polymers) Aqueous solution of water-soluble polymer J: an aqueous solution of a polyether polyol-based urethane polymer (polyurethane-modified polyoxyalkylene) having a number average molecular weight of 68,000 (solid content 47.6%, Adekanol UH-541VF, ADEKA Corporation) Aqueous solution of water-soluble polymer K: an aqueous solution obtained by diluting polyethylene glycol having a number average molecular weight of 20,000 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to a solid content of 50% Aqueous solution of water-soluble polymer L: an aqueous solution obtained by diluting polyethylene oxide having a number average molecular weight of 110,000 (Alcox L-11, Meisei Chemical Industry Co., Ltd.) to a solid content of 50% Aqueous solution of water-soluble polymer M: an aqueous solution obtained by diluting polyethylene glycol having a number average molecular weight of 8,000 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to a solid content of 50% Aqueous solution of water-soluble polymer Y: Aqueous solution of polyethylene glycol with a number average molecular weight of 500,000 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) diluted to a solid content of 50%

[0092] (Fiber substrate) A nonwoven fabric of polyethylene terephthalate (PET) fibers having an average fineness of 0.1 dtex and polyurethane impregnated into the nonwoven fabric, with a PET / polyurethane ratio of 90 / 10, and a basis weight of 530 g / m 2 , 1mm thick fiber substrate.

[0093] [Example 1] The above-mentioned raw materials were mixed to prepare a coating liquid for a surface layer and a coating liquid for an adhesive layer so that the solid content was the following composition: (Coating liquid for surface layer) Polyurethane A 100 parts (95.5%) (parts by mass (% by mass), the same applies below) Nonionic compound E 1.4 parts (1.3%) Water-soluble polymer J 3.4 parts (3.2%) (Coating liquid for adhesive layer) Polyurethane for adhesive layer 100 parts Crosslinking agent 17 parts Leveling agent 0.5 parts Thickener 0.5 parts

[0094] Then, a wet adhesion amount of 120 g / m was applied to the release surface of the release paper. 2 The coating solution for the surface skin layer was applied to the surface of the film for the surface skin layer at a wet coating weight of 130 g / m. 2 The adhesive layer coating liquid was applied to the laminate, and the laminate was heated and dried in a dryer at 90°C for 5 minutes to form an adhesive layer film. The laminate of the surface layer film and adhesive layer film formed on the release paper was then placed on the surface of the fiber substrate so that the adhesive layer films faced each other, and pressed with a flat-plate hot press to bond the fiber substrate and the laminate. The pressing was performed at a temperature of 100°C, a pressure of 5 kgf / cm, and for 10 seconds. After pressing, the laminate was further aged at 70°C for 72 hours to promote crosslinking of the adhesive layer polyurethane.

[0095] The release paper was then peeled off from the laminate thus obtained to obtain the grain-finish leather-like sheet of Example 1, which had a fiber substrate and a resin layer including a skin layer laminated on one side of the fiber substrate. The grain-finish leather-like sheet thus obtained had a skin layer of 50 μm in thickness, a thickness of 0.1 mm, and a basis weight of 640 g / m. 2 The results were shown in Table 1 below.

[0096]

[0097] [Example 2] A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating liquid for the surface layer was used that was prepared so that the solid content had the following composition. The results are shown in Table 1. Polyurethane A 100 parts (95.5%) Nonionic compound E 1.4 parts (1.3%) Water-soluble polymer K 3.4 parts (3.2%)

[0098] [Example 3] A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating liquid for the surface layer was used that was prepared so that the solid content had the following composition. The results are shown in Table 1. Polyurethane A 100 parts (95.5%) Nonionic compound E 1.4 parts (1.3%) Water-soluble polymer L 3.4 parts (3.2%)

[0099] [Example 4] A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating liquid for the surface layer was used that was prepared so that the solid content had the following composition. The results are shown in Table 1. Polyurethane A 100 parts (95.9%) Nonionic compound E 0.8 parts (0.8%) Water-soluble polymer J 3.4 parts (3.3%)

[0100] [Example 5] A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating liquid for the surface layer was used that was prepared so that the solid content had the following composition. The results are shown in Table 1. Polyurethane A 100 parts (92.6%) Nonionic compound E 4.5 parts (4.2%) Water-soluble polymer J 3.4 parts (3.2%)

[0101] [Example 6] A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating liquid for the surface layer was used that was prepared so that the solid content had the following composition. The results are shown in Table 1. Polyurethane A 100 parts (95.5%) Nonionic compound F 1.4 parts (1.3%) Water-soluble polymer J 3.4 parts (3.2%)

[0102] [Example 7] A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating liquid for the surface layer was used that was prepared so that the solid content had the following composition. The results are shown in Table 1. Polyurethane A 100 parts (95.5%) Nonionic compound G 1.4 parts (1.3%) Water-soluble polymer J 3.4 parts (3.2%)

[0103] [Example 8] A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating liquid for the surface layer was used that was prepared so that the solid content had the following composition. The results are shown in Table 1. Polyurethane A 100 parts (95.5%) Nonionic compound I 1.4 parts (1.3%) Water-soluble polymer J 3.4 parts (3.2%)

[0104] [Example 9] A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating liquid for the surface layer was used, which was prepared so that the solid content was the following composition. The results are shown in Table 1. Polyurethane A 100 parts (97.1%) Nonionic compound E 1.4 parts (1.4%) Water-soluble polymer J 1.5 parts (1.5%)

[0105] [Example 10] A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating liquid for the surface layer was used that was prepared so that the solid content had the following composition. The results are shown in Table 1. Polyurethane A 100 parts (90.1%) Nonionic compound E 1.4 parts (1.3%) Water-soluble polymer J 9.5 parts (8.6%)

[0106] [Example 11] A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating liquid for the surface layer was used that was prepared so that the solid content had the following composition. The results are shown in Table 1. Polyurethane B 100 parts (94.4%) Nonionic compound E 2.5 parts (2.4%) Water-soluble polymer J 3.4 parts (3.2%)

[0107] [Example 12] A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating liquid for the surface layer was used that was prepared so that the solid content had the following composition. The results are shown in Table 1. Polyurethane C 100 parts (95.5%) Nonionic compound E 1.4 parts (1.3%) Water-soluble polymer J 3.4 parts (3.2%)

[0108] [Example 13] A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating liquid for the surface layer was used that was prepared so that the solid content had the following composition. The results are shown in Table 1. Polyurethane A 100 parts (97.9%) Nonionic compound E 1.4 parts (1.4%) Water-soluble polymer J 0.7 parts (0.7%)

[0109] [Example 14] A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating liquid for the surface layer was used that was prepared so that the solid content had the following composition. The results are shown in Table 1. Polyurethane A 100 parts (90.2%) Nonionic compound E 1.4 parts (1.2%) Water-soluble polymer M 9.5 parts (8.6%)

[0110] Comparative Example 1 A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating liquid for the surface layer was used that was prepared so that the solid content had the following composition. The results are shown in Table 1. Polyurethane A 100 parts (96.1%) Nonionic compound E 0.6 parts (0.6%) Water-soluble polymer J 3.4 parts (3.3%)

[0111] Comparative Example 2 A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating liquid for the surface layer was used that was prepared so that the solid content had the following composition. The results are shown in Table 1. Polyurethane A 100 parts (92.3%) Nonionic compound H 5.0 parts (4.6%) Water-soluble polymer J 3.4 parts (3.1%)

[0112] Comparative Example 3 A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating liquid for the surface layer was used that was prepared so that the solid content was the following blend composition. The results are shown in Table 1. Polyurethane D 100 parts (90.1%) Nonionic compound E 1.4 parts (1.3%) Water-soluble polymer J 9.5 parts (8.6%)

[0113] Comparative Example 4 A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating liquid for the surface layer was used that was prepared so that the solid content had the following composition. The results are shown in Table 1. Polyurethane A 100 parts (100%)

[0114] Comparative Example 5 A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating liquid for the surface layer was used that was prepared so that the solid content had the following composition. The results are shown in Table 1. Polyurethane A 100 parts (96.7%) Water-soluble polymer J 3.4 parts (3.3%)

[0115] Comparative Example 6 A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating solution for the surface layer was used that had the following solid content composition: Polyurethane A 100 parts (99.4%) Nonionic compound E 0.6 parts (0.6%)

[0116] Comparative Example 7 A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating liquid for the surface layer was used that was prepared so that the solid content had the following composition. The results are shown in Table 1. Polyurethane A 100 parts (95.5%) Nonionic compound X 1.4 parts (1.3%) Water-soluble polymer J 3.4 parts (3.2%)

[0117] Comparative Example 8 A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating liquid for the surface layer was used that was prepared so that the solid content had the following composition. The results are shown in Table 1. Polyurethane A 100 parts (95.5%) Nonionic compound E 1.4 parts (1.3%) Water-soluble polymer Y 3.4 parts (3.2%)

[0118] Comparative Example 9 A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating liquid for the surface layer was used that was prepared so that the solid content had the following composition. The results are shown in Table 1. Polyurethane A 100 parts (87.8%) Nonionic compound E 4.5 parts (3.9%) Water-soluble polymer J 9.5 parts (8.3%)

[0119] Comparative Example 10 A grain-finish leather-like sheet was prepared and evaluated in the same manner as in Example 1, except that a coating liquid for the surface layer was used that was prepared so that the solid content had the following composition. The results are shown in Table 1. Polyurethane E 100 parts (92.3%) Nonionic compound H 5 parts (4.6%) Water-soluble polymer J 3.4 parts (3.1%)

[0120] Referring to Table 1, the present invention relates to a composition containing polyurethane, a nonionic compound having an HLB value of 10 to 16, and a water-soluble polymer, and having a polar component of 25 to 40 mJ / m 2 and the dispersion component is 30 to 40 mJ / m 2 The grain-finish leather-like sheets obtained in Examples 1 to 14, each having a surface layer of the above formula, had a wettability of "medium" or better, a water resistance of "good" or better, and a secondary adhesion of "good" or better.

[0121] On the other hand, the content of nonionic compounds is too low, so the polar component is 25 mJ / m 2 The grain-finish leather-like sheet obtained in Comparative Example 1, in which the HLB value was less than 10, had poor wettability. The grain-finish leather-like sheet obtained in Comparative Example 2, in which a nonionic compound with an HLB value of less than 10 was used, had a polar component of 25 mJ / m2 even when the content of the nonionic compound was increased. 2 The grain-finish leather-like sheet obtained in Comparative Example 3, which used aqueous polyurethane with low polar and dispersive components, also had a polar component of 25 mJ / m2 even when a large amount of water-soluble polymer was added. 2 Less than 30mJ / m 2 Since the thickness was less than 100 μm, the wettability was low and the secondary adhesiveness was also poor.

[0122] It also does not contain nonionic compounds or water-soluble polymers, and the polar component is 25 mJ / m2 The grain-finish leather-like sheet obtained in Comparative Example 4, in which the grain-finish leather-like sheet had a water resistance of less than 100%, had low wettability, and also had poor secondary adhesiveness.

[0123] In addition, the grain-finish leather-like sheet obtained in Comparative Example 4, in which only a water-soluble polymer was blended in the surface layer, also had a polar component of 25 mJ / m 2 Because the thickness was less than 100 μm, the secondary adhesion was improved, but the wettability was low.

[0124] In addition, the grain-finish leather-like sheet obtained in Comparative Example 6, which contained only a nonionic compound in the surface layer in comparison with the grain-finish leather-like sheet obtained in Comparative Example 4, also had a polar component of 25 mJ / m 2 Because the thickness was less than 100 μm, the secondary adhesion was improved, but the wettability was low.

[0125] The grain-finish leather-like sheet obtained in Comparative Example 7, in which a nonionic compound with an HLB value of more than 16 was used in the surface layer, also had a polar component of 25 mJ / m 2 The grain-finish leather-like sheet obtained in Comparative Example 8, which used a water-soluble polymer with a high number-average molecular weight, also had a polar component of 25 mJ / m 2 Since the temperature was less than 100°C, the wettability was improved, but the water resistance and secondary adhesion were reduced.

[0126] The grain-finish leather-like sheet obtained in Comparative Example 9, which contained a high proportion of a nonionic compound with an HLB value of 12 and a water-soluble polymer, had a polar component of 40 mJ / m 2 The grain-finish leather-like sheet obtained in Comparative Example 10 using aqueous polyurethane with a high dispersing component also had a dispersing component of 40 mJ / m because the dispersing component exceeded 40 mJ / m. 2 Although the water resistance was improved due to the temperature exceeding 100°C, the wettability and secondary adhesion were reduced.

[0127] REFERENCE SIGNS LIST 1 Fiber substrate 2 Resin layer 2a Surface layer 2b Intermediate layer 2c Adhesive layer 10 Grain-finish leather-like sheet

Claims

1. It comprises a fibrous substrate and a resin layer laminated on one surface of the fibrous substrate, The resin layer at least includes an epidermal layer, The epidermal layer, contains polyurethane, a nonionic compound with an HLB value of 10 to 16, and a water-soluble polymer, and has a surface free energy analyzed by the Owens-Wendt-Rabel-Kaelble method, with a polar component of 25 to 40 mJ / m 2 and a dispersion component of 30 to 40 mJ / m 2 A silver-coated leather-like sheet having such a surface free energy.

2. The polyurethane has a surface free energy analyzed by the Owens-Wendt-Rabel-Kaelble method, with a polar component of 5 to 20 mJ / m 2 and a dispersion component of 30 to 40 mJ / m 2 The silver-coated leather-like sheet according to Claim 1.

3. The polyurethane is an aqueous polyurethane. The silver-coated leather-like sheet according to Claim 1 or 2.

4. The silver-coated leather-like sheet according to Claim 1 or 2, wherein the nonionic compound includes at least one of a silicone-based compound and an acetylene glycol-based compound.

5. The silver-coated leather-like sheet according to Claim 1 or 2, wherein the epidermal layer contains 0.8 to 5.0% by mass of the nonionic compound.

6. The silver-coated leather-like sheet according to Claim 1 or 2, wherein the water-soluble polymer has a number average molecular weight of 10,000 to 150,000.

7. The silver-coated leather-like sheet according to Claim 1 or 2, wherein the epidermal layer contains 1.0 to 10% by mass of the water-soluble polymer.

8. The silver-coated leather-like sheet according to Claim 1 or 2, wherein the water-soluble polymer includes polyurethane-modified polyoxyalkylene.

9. The silver-attached leather-like sheet according to claim 1 or 2, wherein the skin layer is a continuous film having no pores with a thickness of 10 to 100 μm.

10. The silver-attached leather-like sheet according to claim 1 or 2, wherein the resin layer includes an adhesive layer containing polyurethane with a thickness of 30 to 120 μm for adhering the fiber base material.